Two white, vintage office armchairs with height adjustable swivel bases.
Known as the Hille Polypropylene armchair, it was designed by Robin Day in 1963 for S. Hille & co. "It is now so iconic, it was selected as one of eight designs in a 2009 series of British stamps of 'British Design Classics'", according to Wikipedia.
Hille chairs were manuafctured for different institutions, industries and homes in 40 countries around the world. In South Africa this was done by Afristeel in Booysens, Johannesburg in the 1960's.
"The brief from Hille was for a low cost, mass-produced stacking chair, affordable by all and to meet virtually every seating requirement. Over time it became available in a wide variety of colours and with different forms of base and upholstery. These variations have included Series E for children, made in five sizes with lifting holes, and Polo with rows of graduated circular holes making it suitable for outdoor use.
The one-piece seat and back was injection moulded from polypropylene, a lightweight thermoplastic with a high impact resistance. Polypropylene was invented by an Italian scientist, Giulio Natta, in 1954."